Hello,
I just wanted to mention one thing which is public but not widely recognized:
On older models you could enter the camera's debug mode with the help of some text files on the sd card - if you knew the right filename and some other commands as well.
The activation sequence and filename for the K-5 up until today was never found out as far as I know.
Nevertheless a very nice guy who programmed a tethering software now added a button "Camera debug mode on" to his software and
it does work on the K-5!
You can find the software here:
PK_Tether | Tethering and remote control software for Pentax DSLR cameras
It works only with the newest Version 0.6.
Naturally doing this is for the not risk averse people (might do all sort of damaging things to your camera) as it's not meant to be done by users, but...